Semiconductor wafers are commonly used as substrates in the production of integrated circuit chips. Chip manufacturers require wafers that have extremely flat and parallel surfaces to ensure that a maximum number of chips can be fabricated from each wafer. After being sliced from an ingot, wafers typically undergo grinding and polishing processes designed to improve certain surface features, such as flatness and parallelism.
Simultaneous double side grinding operates on both sides of a wafer at the same time and produces wafers with highly planarized surfaces. Grinders that perform double side grinding include, for example, those manufactured by Koyo Machine Industries Co., Ltd. These grinders use a wafer clamping device to hold the semiconductor wafer during grinding. The clamping device typically comprises a pair of hydrostatic pads and a pair of grinding wheels. The pads and wheels are oriented in opposed relation to hold the wafer therebetween in a vertical orientation. The hydrostatic pads beneficially produce a fluid barrier between the respective pad and wafer surface for holding the wafer without the rigid pads physically contacting the wafer during grinding. This reduces damage to the wafer that may be caused by physical clamping and allows the wafer to move (rotate) tangentially relative to the pad surfaces with less friction. While this grinding process can improve flatness and/or parallelism of the ground wafer surfaces, subsequent processes can impact the wafer and cause topology degradation. For example, as a result of lattice mismatch between a heavily doped substrate and a lightly doped epitaxial layer, a bow and a warp of the wafer changes substantially after the epitaxial layer deposition. Such warp changes may be drastic and result in wafer capability degradation and/or yield losses. As such, undesirable topography features introduced into the wafer by the epitaxial layer deposition cannot be controlled.
This Background section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.